jQuery.extend({
    createUploadIframe: function(id, uri) {
		//create frame
		var frameId = 'jUploadFrame' + id;
		
		if(window.ActiveXObject) {
			var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
			if(typeof uri== 'boolean'){
				io.src = 'javascript:false';
			} else if(typeof uri== 'string') {
				io.src = uri;
			}
		} else {
			var io = document.createElement('iframe');
			io.id = frameId;
			io.name = frameId;
		}
		io.style.position = 'absolute';
		io.style.top = '-1000px';
		io.style.left = '-1000px';
		
		document.body.appendChild(io);
		
		return io			
    },
	
	createUploadForm: function(id, fileElementId) {
		//create form
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;
		var form = $('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');	
		var oldElement = $('#' + fileElementId);
		var newElement = $(oldElement).clone();

		$(oldElement).attr('id', fileId);
		$(oldElement).before(newElement);
		$(oldElement).appendTo(form);
		//set attributes
		$(form).css('position', 'absolute');
		$(form).css('top', '-1200px');
		$(form).css('left', '-1200px');
		$(form).appendTo('body');		

		return form;
	},

	ajaxFileUpload: function(s) {
		// TODO introduce global settings, allowing the client to modify them for all requests, not only timeout		
		s = jQuery.extend({}, jQuery.ajaxSettings, s);
		var id = new Date().getTime()        
		var form = jQuery.createUploadForm(id, s.fileElementId);
		var io = jQuery.createUploadIframe(id, s.secureuri);
		var frameId = 'jUploadFrame' + id;
		var formId = 'jUploadForm' + id;
		
		// Watch for a new set of requests
		if ( s.global && ! jQuery.active++ ) {
			jQuery.event.trigger( "ajaxStart" );
		}            
		var requestDone = false;
		// Create the request object
		var xml = {}   
		if ( s.global ) jQuery.event.trigger("ajaxSend", [xml, s]);
		// Wait for a response to come back
		var uploadCallback = function(isTimeout) {			
			var io = document.getElementById(frameId);
            try {				
				if (io.contentWindow) {
					xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
					xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
				} else if(io.contentDocument) {
					xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
					xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
				}
            } catch(e) {
				jQuery.handleError(s, xml, null, e);
			}
			if ( xml || isTimeout == "timeout") {				
				requestDone = true;
				var status;
				try {
					status = isTimeout != "timeout" ? "success" : "error";
					// Make sure that the request was successful or notmodified
					if ( status != "error" ) {
						// process the data (runs the xml through httpData regardless of callback)
						var data = jQuery.uploadHttpData( xml, s.dataType );    
						// If a local callback was specified, fire it and pass it the data
						if ( s.success ) s.success( data, status );
    
                        // Fire the global callback
						if( s.global ) jQuery.event.trigger( "ajaxSuccess", [xml, s] );
					} else {
						jQuery.handleError(s, xml, status);
					}
                } catch(e) {
					status = "error";
					jQuery.handleError(s, xml, status, e);
				}

                // The request was completed
                if ( s.global ) {
					jQuery.event.trigger( "ajaxComplete", [xml, s] );
				}

                // Handle the global AJAX counter
                if ( s.global && ! --jQuery.active ) {
					jQuery.event.trigger( "ajaxStop" );
				}

                // Process result
                if ( s.complete ) {
					s.complete(xml, status);
				}

                jQuery(io).unbind();

                setTimeout(function() {
					try {
							$(io).remove();
							$(form).remove();	
							
						} catch(e) 
						{
							jQuery.handleError(s, xml, null, e);
						}									
				
					},
					100);
                xml = null;
            }
        }
        // Timeout checker
        if ( s.timeout > 0 ) {
            setTimeout(function() {
                // Check to see if the request is still happening
                if( !requestDone ) {
					uploadCallback( "timeout" );
				}
            },
			s.timeout);
        }
		
        try {
           // var io = $('#' + frameId);
			var form = $('#' + formId);
			$(form).attr('action', s.url);
			$(form).attr('method', 'POST');
			$(form).attr('target', frameId);
            if(form.encoding) {
                form.encoding = 'multipart/form-data';				
            } else {				
				form.enctype = 'multipart/form-data';
            }			
            $(form).submit();
        } catch(e) {			
			jQuery.handleError(s, xml, null, e);
        }
		
		if (window.attachEvent) {
			document.getElementById(frameId).attachEvent('onload', uploadCallback);
		} else {
			document.getElementById(frameId).addEventListener('load', uploadCallback, false);
		} 		
        
		return {
			abort: function () {}
		};
    },

    uploadHttpData: function( r, type ) {
        var data = !type;
		
        data = type == "xml" || data ? r.responseXML : r.responseText;
        // If the type is "script", eval it in global context
        if ( type == "script" ) {
            jQuery.globalEval( data );
		}
        // Get the JavaScript object, if JSON is used.
        if ( type == "json" ) {
            eval( "data = " + data );
		}
        // evaluate scripts within html
        if ( type == "html" ) {
            jQuery("<div>").html(data).evalScripts();
			//alert($('param', data).each(function(){alert($(this).attr('value'));}));
		}
		
        return data;
    }
})

